#include <iosfwd>

class big_int
{
public:
	big_int() {}
	explicit big_int(int) {}
	big_int(big_int const &) {}

	big_int & operator=(big_int const &) { return *this; }

	big_int operator-() const { return *this; }

    big_int & operator+=(big_int const &) { return *this; }
    big_int & operator-=(big_int const &) { return *this; }
    big_int & operator*=(big_int const &) { return *this; }
    big_int & operator/=(big_int const &) { return *this; }
    big_int & operator%=(big_int const &) { return *this; }

	void swap(big_int &) {}
};

big_int operator+(big_int const & a, big_int const & b) { return a; }
big_int operator-(big_int const & a, big_int const & b) { return a; }
big_int operator*(big_int const & a, big_int const & b) { return a; }
big_int operator/(big_int const & a, big_int const & b) { return a; }
big_int operator%(big_int const & a, big_int const & b) { return a; }

bool operator==(big_int const &, big_int const &) { return true; }
bool operator!=(big_int const &, big_int const &) { return true; }

bool operator<(big_int const &, big_int const &) { return true; }
bool operator<=(big_int const &, big_int const &) { return true; }

bool operator>(big_int const &, big_int const &) { return true; }
bool operator>=(big_int const &, big_int const &) { return true; }

std::ostream & operator<<(std::ostream & out, big_int const &) { return out; }
std::istream & operator>>(std::istream & in, big_int &) { return in; }

big_int abs(big_int const & a) { return a; }
